audio: Add AIDL definitions for Playback/RecordTrackMetadata

These types are used by I/O streams of the Audio HAL and
also by other HALs, so they are placed into 'a.h.audio.common'
types-only package.

Bug: 198812639
Test: m android.hardware.audio.common
Test: m check-vintf-all
Change-Id: I7064c3819d4c8e61981542ca2ccc52ca992a4ef8